Dean wasn't someone who often let his guard down - not entirely. Dunwich hadn't exactly lured him into sense of security, either. So his eyes were sharp, and through the mirror he caught Cinna holding the scissors in a way Dean wasn't sure lent itself to cutting hair very well.
"Thought he was a ghost." He said, careful not to out Thomas just in case he hasn't been honest with Cinna about what he was. "Salt in my world will get temporarily get rid of ghosts. Imagine my surprise when he glared at me instead." He chuckled. "Bought him coffee after that and apologized. Ghosts in my world are... pretty violent. Can't be too careful."